The present invention is directed generally to optical communication systems. More particularly, the invention relates to the control and operation of optical systems and optical components, such as amplifiers, transmitters, receivers, switches, add/drop multiplexers, filters, etc., and the optical links and networks comprising the systems.
Fiber optic transmission systems generally involve numerous optical links that are arranged in point to point, ring, mesh, or other configurations which are interconnected to provide communication services over a geographic region. Each of the various links must be managed and operated to ensure the proper flow of communications traffic within the link. The interconnection of the various links requires additional management oversight and control to ensure the smooth flow communications traffic between the various transmission links in the system.
As used herein, communications traffic should be interpreted in its broadest sense to include audio, video, data, and other forms of information that can be optically transferred. Likewise, the term “system” should be broadly construed to include a single linear link consisting of an optical transmitter and an optical receiver, as well as optical networks including pluralities of diversely located transmitters and receivers that are interconnected by one or more optical fibers and various optical components, such as optical switches, amplifiers, add/drop devices, filters, equalizers, etc.
The necessity of simultaneously managing the individual transmission links and a network of links has led to the development of standardized hierarchical approaches to optical network management. One such standardized structure, known as the Telecommunication Management Network (“TMN”) structure, allocates the management responsibilities over number of management levels, as generally shown in FIG. 1.
In the TMN structure, a Network Management Layer (“NML”) performs monitoring and control functions on a network basis. High level network tasks, such as establishing network connectivity including establishing primary and protection paths and wavelength management functions are performed through the NML. A Service Management Layer (“SML”) is provided for communications service providers to interface with one or more NML reporting to the service layer. The SML is used to provision the network as required to meet communication traffic patterns in the system and report to service configuration to a Business Management Layer (“BML”) of the service provider.
The TMN structure separates the network management functions into two layers to provide a hierarchical division of the management functions. The NML receives high-level network configuration instructions from the SML and develops a general set of element instructions necessary to implement the network instructions. The NML sends the general element instructions to an Element Management Layer (“EML”), in which a plurality of element managers are typically used to oversee a Network Element Layer (“NEL”). The NEL includes the optical components and associated hardware that comprise the actual transmission system and which are generally referred to as network elements (“NE”). Each network element, or optical component, generally includes a network element, or optical component, controller that controls the operation of the component in accordance with the specific element instructions from the element manager.
Communication between the various TMN layers is generally follows established protocols, such as SNMP (Signaling Network Management Protocol), CMIP (Common Management Information Protocol), CORBA (Common Object Request Broker Architecture), Java, Q3, etc. The network and element managers and the component controllers generally are configured according to protocols, such as GDMO (Guideline for Definition of Managed Objects) and its derivatives, as well as other standard protocols. Whereas, the component controller typically controls the sub-components using proprietary protocols particular to the optical system.
In the operation of the optical system, element managers are generally assigned to one or more network elements that will usually, but not necessarily, be interconnected in one or more specific links, or segments, in the network. The network manager sends the general element instructions to the element managers. Each element manager generates specific element instructions for its managed network elements from the general element instructions. The specific network element instructions can be distributed directly to optical components either, for example via a local, metropolitan, or wide area network (LAN, MAN, or WAN, respectively). Alternatively, specific network element instructions can be distributed remotely via a supervisory or service channel that provides communication between the network elements in the NEL.
The component controller not only receives and processes the specific element instructions, but controls all work functions performed in the component including those performed by component peripherals, or sub-components, such as pumps, heaters, coolers, current sources, etc. The component controller also monitors the sub-component performance and provides status information to the element manager for higher level and/or redundant analysis and monitoring.
In many systems, the operation of the sub-components in the optical component are controlled by the component controllers and performed with reference to one or more Management Information Bases (MIBs). The MIBs provide operational parameters for each controllable portion of the component as a function of monitored operating characteristics of the optical components. The component controller monitors the operating characteristics and controls the operation of the component and its sub-components in accordance with its associated MIBs.
The element managers monitor the performance of the network elements/optical components for compliance with the general element instructions and generate element status reports on the network element status. The network manager monitors the element status reports from the element managers to ensure compliance with the network instructions and provides a network report with respect to the network instructions to the service manager.
A shortcoming with conventional TMN based systems is that control of the actual operation of the optical system has been pushed down through the management hierarchy to the network element level. Thus, the TMN structure involves a plurality of management layers that provide oversight responsibilities, but the component controllers are solely responsible for control of multiple tasks that must be coordinated and monitored to ensure correct operation of the component. As such, the component controller represents a single point of failure that could disable the component, as well as a link and possibly larger segments of the network.
The traditional view toward addressing the risk of a component controller failure has been to provide controllers having increased processing power and reliability or redundant controllers. However, the use of higher performance component controllers does not ameliorate the consequences of a component controller failure, but merely reduces the risk of component failure. High performance controllers also tend to increase the local heat generation of the component, which increases the cooling requirements of the system. Whereas, redundant controllers provide additional protection against a controller failure, but further increases the complexity of the control structure, thereby increasing the probability of a controller malfunction. In view of the substantial problems that can result from component controller failures and malfunctions, it would be desirable to have a network management structure that reduces the risks associated with component controller failures to provide robust optical systems.